21020043 has 16 divisors (see below), whose sum is σ = 30865536. Its totient is φ = 12618240.

The previous prime is 21020039. The next prime is 21020053. The reversal of 21020043 is 34002012.

It is not a de Polignac number, because 21020043 - 2² = 21020039 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21020053) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 555 + ... + 6507.

It is an arithmetic number, because the mean of its divisors is an integer number (1929096).

Almost surely, 2^21020043 is an apocalyptic number.

21020043 is a deficient number, since it is larger than the sum of its proper divisors (9845493).

21020043 is a wasteful number, since it uses less digits than its factorization.

21020043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6074.

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21020043 is about 4584.7620439888. The cubic root of 21020043 is about 275.9801629305.

Adding to 21020043 its reverse (34002012), we get a palindrome (55022055).

The spelling of 21020043 in words is "twenty-one million, twenty thousand, forty-three".